Hydraulic pushbutton assembly



Aug. 23, 1966 F. T. BILEK 3,268,673

HYDRAULIC PUSHBUTTON ASSEMBLY Filed May 1965 R\ m MLI a mi N j,INVENTOR. f5 67/ United States Patent O 3,268,673 HYDRAULIC PUSHBUTTONASSEMBLY Frank Thomas Bilek, Downers Grove, Ill., assignor to Thisinvention relates to pushbuttons generally and more particularly tohydraulic interlocking pushbutton assemblies.

Pushbuttons and related assemblies have many uses as, for example, ontelephones, adding machines, coin control devices, and the like. As agenerality, a designer of these pushbuttons faces two problems. A firstproblem is to exert restoring forces upon the buttons to return them toa normal position. A second problem is to provide mechanical interlocksso that only a specified number and no morebuttons may be depressed atany given time. Heretofore, these and other problems have been solved byinterconnecting the pushbuttons by means of expensive and complexmechanical linkages. Among other things, this means that every differentlinkage requirement involves a redesign, new tooling, etc.

An object of the invention is to provide new and improved pushbuttonassemblies. More particularly, an object is to provide interlockingpushbuttonsof a simple, inexpensive design. Yet-another object is toprovide highly reliable devices having an interlocking pushbutton actionwhich give a long, trouble-freev lifetime of service.

Another object is to provide pushbutton assemblies which may beconstructed on standard machine tools from readily available commercialparts. Moreover, an object is to provide for the construction of avirtually unlimited number of interlocking arrangements with few or nochanges of piece parts.

In accordance with one aspect of this invention, a pushbutton assemblyincludes a numberof pistons or other fluid displacement meansindividually associated with each pushbutton. Each displacement means isconnected via a fluid passage to a reservoir. Before filling thereservoir, one or more of the pushbuttons are pressed. Then thereservoir isfilled to capacity with a noncompressible fluid such ashydraulic fluid. Thus, if one pushbutton was depressed when thereservoir was filled, :a depressed pushbutton must raise if any otherpushbutton is pushed. If two pushbuttons were depressed when thereservoir was filled, two buttons raise if two are pushedsimultaneously. One obvious advantage is that the same piece parts maybe used for different assembliesthe only manufacturing differences arethe number of pushbuttons that are depressed when the reservoir isfilled. i

The above mentioned and other features of this invention and the mannerof obtaining them will become more apparent, and the invention itselfwill be best understood by references to the following description of anembodiment of the invention taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of a pushbutton assembly;

FIG. 2 is a fragmentary cross section view of a single pushbuttonsuperstructure showing how contact springs may be actuated;

FIG. 3 shows, in cross section, a first embodiment of a pushbuttonassembly; 7

FIG. 4 shows a cross section view of a two-step pushbutton;

FIG. 5 shows a cross section view of pushbuttons hav- 3,268,673 PatentedAugust 23, 1966 ice FIG. 8 is a perspective view of a telephone subsetincorporating an exemplary pushbutton assembly.

A manually operated pushbutton assembly is shown in FIG. 1 to illustratea preferred embodiment exemplifying the principles of the invention. Ingeneral, this embodiment includes a plurality of pushbuttons 10 mountedon a reservoir 11. The reservoir 11 stores a noncompressible fluid-suchas a hydraulic fluid, for example. Mounted on the reservoir 11 are aplurality of fluid displacement means 12, each containing apredetermined amount of the non-compressible fluid in directcommunication with the fluid in the reservoir 11. In this exemplaryembodiment, each of the fluid displacement means is a rubber or plasticbellows 13 sealed to the reservoir 11 by a device, such as a threadedcollar 14. The bellows could also be made of a metal such as'a Phosphorbronze, for example. In addition, a device (not shown) such as anovercenter spring will snap down to hold a key when it is' depressed.

A fluid displacement means is individually associated with each of thepushbuttons. For example, an expanded bellows 13, individuallyassociated with pushbutton 15, holds a predetermined volume of hydraulicfluid. On the other hand, 'the compressed bellows 16 has expelled acertain amount of hydraulic fluid into the reservoir 11. In doing so, itforced any other depressed pushbuttons to rise. FIG. 2 shows a fragmentof a superstructure assembly for guiding and supporting the pushbuttons10. In greater detail, the superstructure of FIG. 2 includes a baseplate 20 having a number of guideway apertures formed therein (as at 21,for example) for supporting the stem 22 of pushbutton 23. Depending frombase plate 29 are one or more sets of contact springs 24. The stem 22carries a portion formed at the top to butt against the base plate 20and limit upward pushbutton motion and at the bottom to provide forcausing contact spring motion. That is, the lower edge of portion 25 andsprings 24 have complementary cam surfaces which translate downwardpushbutton motion into leftward (as viewed in FIG. 2) spring motion. Thespring returns to normal under its own spring tension when thepushbutton raises- In a second embodiment of the invention, FIG. 3, thereservoir 30 has a number of upstanding cylinder walls formed therein,as shown at 31, for example. The lower portion 32 of each pushbutton isshaped in the form of a piston sealed against the cylinder wall by meansof one or more piston rings 33which could be simple rubber 0 rings forexample. The right-hand pushbutton controlled piston 34 is shown withthree piston rings. One end of the reservoir 30 contains a filler plug35 and the other end contains an-air vent 36.

To complete the embodiments of either FIG. 1 or FIG. 3, it is onlynecessary to be certain that the required number of pushbuttons aredepressed and that all remain ing pushbuttons are fully raised. Forexample, pushbutton controlled piston 34 is depressed and pushbutton 32is raised. Then, the filler plug 35 is removed and the reservoir 30 isfilled to capacity with a hydraulic fluid. A second plug 36 may beopened slightly to bleed air from the system. By inspection, it shouldbe obvious that if reservoir 30 is completely filled with anon-compressible fluid and if pushbutton 32 is pushed down, pushbutton34 must rise. I

Those skilled in the art will readily perceive how various full-step andhalf-step contact operations may be provided by controlling the amountof fluid placed in the reservoir. To insure exact half-step operations,springs, retaining clips, catches, or other mechanical aids may be usedto restrain or restrict pushbutton motion at not only the full but alsothe half-step. To illustrate one such aid, FIG. 4 shows a rubber O ring40 adapted to restrain pushbutton motion at any one of three steps41-43. That is the cylinder wall contains three circumferentiallydepressed rings into which the rubber O ring may expand to restrainmotion.

. Moreover, by varying the volume of fluid displaced by each pushbuttonsome buttons may be interlocked so that 'a'single' pushbutton may bedepressed at any given time, and others may be interlocked to allow aplurality of buttons to be depressed simultaneously. For example, FIG.shows a pushbutton controlled piston 45, which displaces twice as muchfluid as the pushbutton controlled pistons 46, 47. Thus, if pushbutton45 is down, it raises to a half-step when button 46 is pushed. Ifbuttons 46, 47 are pushed simultaneously, button 45 raises to its wholestep. If button 45 is then pushed both of the buttons 46, 47 raise.

A reset is provided by a free moving piston 48. If piston 48 is pushedas far as it will go in the direction of arrow 49, all pushbuttons mustrise. When the pushbutton 46 is pushed down, the piston 48 slidesrightward, as viewed in the drawing, to compensate for the displacedfluid. If pushbuttons 46 and 47 are both pushed down, the piston 48slides rightward and hits a stop. If yet another pushbuttonis'thereafter pushed, no further compression relief can result frommovement -of piston 48. Thus, any new depression of a pushbutton (suchas 45) will raise the buttons that are then lowered.

The embodiments of FIGS. 1 and 3 require precision piston ring seals,but they give a more accurate and close tolerance response. If suchaccuracy is not required, the embodiment of FIG. 6 offers a costreduction. Here, the non-compressible fluid is sealed in a flexible bag50. Then the bag is dropped into the reservoir housing 51 and a top issecured into position by any suitable means, such as bolts 52, 53. Thebag of fluid 50 fills the reservoir 51 to the extent required so thatone and only one pushbutton (or any other desired number) may be pusheddown at any given time. For example, pushbutton 54 is shown in FIG. 6 aspushed down and pushbuttons 55, 56 are shown as raised. The downwardpressure on the bag at 57 tensions the bag at 58 and raises the buttons55, 56. Thus, if pushbutton 55 is pushed, the fluid in bag 50 moves tothe side and forces pushbutton 54 to rise.

Means are provided for interlocking the pushbuttons by groups. Moreparticularly, FIG. 7 shows the reservoir as divided into two distinctsections 60, 61 by a series of check valves 62. The check valves arehere shown as a pair of spring loaded balls 63, 64 adapted to seat underthe spring tension for the purpose of preventing fluid movement betweensections 60, 61. If pushbutton 65 should be down when button 66 ispushed, button 65 raises. Neither pushbutton 67 nor pushbuttons 68 canbe pushed because reservoir 61 is completely full and check valve 64prevents the passage of fluid from section 61 to section 60.

If pushbutton 69 is pushed, two pins a, b push balls 63, 64 down, thusopening the check valves. The fluid that pushbutton 69 displaces raisedthe buttons 65 or 66. Now buttons 67, 68 can be pushed because the fluidthat they displace flows through the check valves 63, 64 to section 60.Thereafter, pushbuttons 67, 68 can be operated, but pushbuttons 65, 66are locked in a raised position until after pushbutton 69 is againdepressed to open the check valves.

The pedadogics of this specification should be clear from a readingthereof. That is, I provide a series of fragmentary drawings, eachexplaining one or more distinct principles or features of the invention.Thus, FIG. 2 shows how to operate electrical contacts responsive topushbutton motion. FIG. 3 shows how to seal pistons against cylinderwalls. FIG. 5 shows howv to reset the pushbuttons and how pushbuttonsmay be given a differential motion to provide the well known two-stepcontact motion commonly called X or preliminary contacts in theautomatic telephone art. FIG. 4 shows an exemplary 4 way of givingdiscrete positions to the two-step pushbutton motion of FIG. 5.

My invention relates to a way of providing mechanically interlockedpush-buttons for selectively controlling electrical circuits. When soproviding such interlocking pushbuttons, the design engineer will beexpected to adapt any or all of these principles and features to hisparticular needs. He is not expected to treat the reset button 48 asapplicable only to the differential motion pushbuttons of FIG. 5. Norshould he treat the discrete half-step positioning means as applicableonly to FIG. 4. Quite the contrary, he is expected to use anycombinations of the many features in conjunction with any of the varioushydraulic systems. To emphasize this point, I have shown the resetbutton 48 not only in FIG. 5, but also in FIGS.

1 and 7I could also have shown a reset button in other figures. In likemanner, to indicate that the differential pushbuttons are not limited tothe FIG. 5 disclosure, I have shown the pushbutton 68 as controlling twopistons 46, 47, each piston displacing one-half the fluid that thepiston 67 displaces. I could also show some of the bellows 13 as beinglarger than others, and button 54 could displace twice as much fluid aseither of the buttons 55, 56.

Obviously, the argument could be extended to all of the features that Ihave shown. Therefore, no one should construe the separate featuredrawings, which were dictated by the pedagogics of the specification, asan indication that the individual features are limited to any particularapplication of the invention.

Although those skilled in the art will readily perceive many uses forthe pushbuttons, FIG. 8 shows one such assembly 70 used in conjunctionwith a telephone 71. The pushbuttons could also be used to replace thedial 72.

While the principles of the invention have been de scribed above inconnection with specific apparatus and application, it is to beunderstood that this description is made only by way of example and notas a limitation on the scope of the invention.

I claim:

1. An electrical control device comprising a multi-line telephone set,means including an assembly of pushbuttons for selectively connectingsaid telephone to any one of said telephone lines, said pushbuttonassembly means comprising a reservoir holding a non-compressiblehydraulic fluid, a plurality of communicating hydraulic cylinders alsofilled with said fluid, pushbutton actuated piston means for selectivelydisplacing the fluid in any one of said cylinders into said reservoirand other of said cylinders, means responsive to said displacement ofsaid fluid for restoring any previously actuated one of said pistonmeans, and con-tact means controlled by each of said pushbuttons forcompleting said selective connection of said telephone to any one ofsaid telephone lines.

2. The device of claim 1 wherein said cylinders comprise a plurality ofbellows communicatingly sealing said cylinders into said reservoir, saidbellows being individually associated with said pushbutton actuatedpiston so that said movement of each of said pushbuttons to a depressedposition compresses an individually associated'one of said bellows toexpel the fluid therein into said reservoir.

3. The device of claim 1 wherein said reservoir is shaped to provide thewalls of said cylinders, said fluid displacement means comprising aplurality of pistons positioned in said cylinders and individuallyassociated with said pushbuttons, and means for sealing said pistonsagainst the walls of said cylinders.

4. In the device of claim 1, means associated with each of saidpushbuttons for restraining pushbutton motion at at least one positionbetween a fully lowered and fully raised position.

5. In the device of claim 1, a freely moving reset means for providing alimited compression relief whereby all of said pushbuttons may be raisedsimultaneously or one or more of said pushbuttons may be lowered.

6. The device of claim 5 wherein said reset compression 5 meanscomprises a piston for resetting said pushbuttons.

7. In the device of claim 5, means for interlocking said pushbuttons bygroups whereby pushbuttons in a first group may be operated andpushbuttons in a second group may not be operated, and means fortransferring said group. interlock from said first to said second groupwhereby the pushbuttons in said first group may not be operated and thepushbuttons in said second group may be operated.

8. In the device of claim 1, check valve means for dividing saidreservoir into independent compartments, a plurality of said pushbuttonsassociated with each of said compartments, means whereby each of saidpushbuttons displaces a predetermined volume of said fluid whendepressed, and means for selectively operating said check valves totransfer fluid between said compartments to lock the pushbuttonsassociated with some of said compartments and unlock the pushbuttonsassociated with other of said compartments.

References Cited by the Examiner UNITED STATES PATENTS 2,240,287 4/1941Croll 6054.5 2,800,034 7/1957 Seeger 2005 X 3,050,605 8/1962 Pollak200-168 3,071,930 1/1963 Moulin 60-54.5

FOREIGN PATENTS 318,566 6/ 1902 France.

ROBERT K. SCHAEFER, Primary Examiner.

R. R. BUNEVICK, KATHLEEN H. CLAFFY, Examiners.

M. GINSBURG, Assistant Examiner.

1. AN ELECTRICAL CONTROL DEVICE COMPRISING A MULTI-LINE TELEPHONE SET,MEANS INCLUDING AN ASSEMBLY OF PUSHBUTTONS FOR SELECTIVELY CONNECTINGSAID TELEPHONE TO ANY ONE OF SAID TELEPHONE LINES, SAID PUSHBUTTONASSEMBLY MEANS COMPRISING A RESERVOIR HOLDING A NON-COMPRESSIBLEHYDRAULIC FLUID, A PLURALITY OF COMMUNICATING HYDRAULIC CYLINDERS ALSOFILLED WITH SAID FLUID, PUSHBUTTON ACTUATED PISTON MEANS FOR SELECTIVELYDISPLACING THE FLUID IN ANY ONE OF SAID CYLINDERS INTO SAID RESERVOIRAND OTHER OF SAID CYLINDERS, MEANS RESPONSIVE TO SAID DISPLACEMENT OFSAID FLUID